Engine Speed (RPM) Sensor G28 , Checking

Engine Speed (RPM) Sensor -G28-, Checking







Recommended special tools and equipment
- VAG1526A multimeter
- VAG1594A connector test kit
- VAG1598/31 test box

NOTE: The engine speed (RPM) sensor -G28-. detects RPM and reference marks. The engine cannot be started without a signal from the engine speed (RPM) sensor -G28-. If the engine speed (RPM) sensor -G28- signal fails while the engine is running, the engine will stop immediately.

Test requirement:
- Ignition switched off.

Work procedure
- Before performing test, check sensor for proper installation and proper fitting.







- Disconnect electrical harness connector -2- to Engine Speed (RPM) sensor -G28-.







NOTE: To reach the harness connectors, the left cover in engine compartment must be removed, the line to Engine Coolant Level (ECL) Warning Switch at bottom on reservoir must be disconnected, bolt (arrow) of coolant reservoir must be unscrewed and set it aside. Coolant hoses -1- to -3- remain connected.

Checking internal resistance







- Connect multimeter between terminal 2 and 3 for resistance measurement.
- Specified value: 730 to 1000 Ohms

NOTE: Resistance value of the engine speed (RPM) sensor is based on a temperature of 20 degrees C. Resistance increases as temperature increases.

If specified value is not obtained:
- Replace Engine Speed (RPM) sensor.

If specified value is obtained:







- Connect multimeter to terminals 2 and 1 (shielding) and to terminals 2 and (shielding) for resistance measurement.
- Specified value: each infinity ohm (no continuity)

If specified value is not obtained:
- Replace Engine Speed (RPM) sensor

If specified value is obtained:

Checking wire connections
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected.







- Check the following wire connections for open circuit according to wiring diagram:

Harness connector Terminal Test box Socket
1 (shielding) 108
2 (Ground (GND)) 90
3 (signal) 82

- Specified value: Wire resistance max 1.5 Ohms
- Check wires for short circuit to each other as well as to B+ and Ground (GND).
- Specified value: Infinity ohm (no continuity)
- If necessary, repair wire connection.

If no malfunctions are detected:
- Replace Engine Control Module (ECM).

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If DTC memory was erased, generate readiness code.

- End diagnosis and switch ignition off.